fix(prompt-gen): auto-update STATE.md and improve skip logic for completed features

- What: skip features with progress.last_done == P4, not just status == READY
- What: auto-update STATE.md when step completes if status is UNKNOWN
- What: add expected_status_for_step() and update_state_status() functions
- What: add tests for new state management functions
- Why: fix issue where completed features (P4) with missing STATE.md would re-run from start

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: trend-denny-lee

src/features/prompt_gen/interactive.rs

@@ -15,7 +15,10 @@ use dialoguer::{theme::ColorfulTheme, Confirm, FuzzySelect, Input, MultiSelect,
 use std::path::{Path, PathBuf};
 
 use super::executor::{CliType, Executor, ExecutorConfig};
-use super::progress::{read_state_status, FeatureInfo, FeatureStatus, Step};
+use super::progress::{
+    expected_status_for_step, read_state_status, update_state_status, FeatureInfo, FeatureStatus,
+    Step,
+};
 
 // ============================================================================
 // 執行模式
@@ -652,8 +655,28 @@ impl InteractiveRunner {
                 feature.progress.mark_done(step, result.session_id);
                 feature.progress.save_to_file(feature.progress_file())?;
 
-                // 更新狀態
-                feature.status = read_state_status(feature.state_file())?;
+                // 自動更新 STATE.md（如果 LLM 沒有更新的話）
+                let expected_status = expected_status_for_step(step);
+                let current_status = read_state_status(feature.state_file())?;
+
+                // 只有當狀態落後或未知時才自動更新
+                if current_status == FeatureStatus::Unknown
+                    || (step == Step::P4 && !current_status.is_ready())
+                {
+                    update_state_status(
+                        feature.state_file(),
+                        &feature.feature_key,
+                        expected_status.clone(),
+                    )?;
+                    feature.status = expected_status;
+                    println!(
+                        "{} STATE.md 已自動更新: {}",
+                        style("[狀態]").magenta(),
+                        feature.status
+                    );
+                } else {
+                    feature.status = current_status;
+                }
 
                 println!(
                     "{} 進度已保存: {}",
@@ -717,12 +740,19 @@ impl InteractiveRunner {
             let feature_dir = self.features[idx].feature_dir.clone();
             self.features[idx] = FeatureInfo::load_from_dir(&feature_dir, &feature_key)?;
 
-            // 檢查是否已完成
-            if self.features[idx].status.is_ready() {
+            // 檢查是否已完成（P4 完成或 status 為 READY）
+            let is_completed = self.features[idx].progress.last_done == Step::P4
+                || self.features[idx].status.is_ready();
+            if is_completed {
                 println!(
-                    "{} 功能 {} 已就緒，跳過",
+                    "{} 功能 {} 已完成 ({}), 跳過",
                     style("[跳過]").dim(),
-                    style(&feature_key).cyan()
+                    style(&feature_key).cyan(),
+                    if self.features[idx].status.is_ready() {
+                        "READY"
+                    } else {
+                        "P4 done"
+                    }
                 );
                 continue;
             }

src/features/prompt_gen/progress.rs

@@ -287,6 +287,62 @@ pub fn read_state_status<P: AsRef<Path>>(state_file: P) -> Result<FeatureStatus>
     Ok(FeatureStatus::Unknown)
 }
 
+/// 根據步驟取得預期狀態
+pub fn expected_status_for_step(step: Step) -> FeatureStatus {
+    match step {
+        Step::None => FeatureStatus::Unknown,
+        Step::P1 => FeatureStatus::P1DoneIntDeployed,
+        Step::P2 => FeatureStatus::P2E2EPassed,
+        Step::P3 => FeatureStatus::P3RefactoredIntDeployed,
+        Step::P4 => FeatureStatus::Ready,
+    }
+}
+
+/// 更新 STATE.md 檔案中的狀態
+pub fn update_state_status<P: AsRef<Path>>(
+    state_file: P,
+    feature_key: &str,
+    new_status: FeatureStatus,
+) -> Result<()> {
+    let path = state_file.as_ref();
+    let status_str = new_status.to_string();
+
+    // 確保父目錄存在
+    if let Some(parent) = path.parent() {
+        std::fs::create_dir_all(parent)?;
+    }
+
+    if path.exists() {
+        // 更新現有檔案
+        let content = std::fs::read_to_string(path)
+            .with_context(|| format!("無法讀取狀態檔案：{}", path.display()))?;
+
+        let re = Regex::new(r"STATUS[：:]\s*\S+")?;
+
+        let new_content = if re.is_match(&content) {
+            // 替換現有 STATUS
+            re.replace(&content, format!("STATUS: {}", status_str))
+                .to_string()
+        } else {
+            // 在檔案開頭加入 STATUS
+            format!("STATUS: {}\n\n{}", status_str, content)
+        };
+
+        std::fs::write(path, new_content)
+            .with_context(|| format!("無法寫入狀態檔案：{}", path.display()))?;
+    } else {
+        // 建立新檔案
+        let content = format!(
+            "# {} State\n\nFEATURE_KEY: {}\nSTATUS: {}\n\n## Notes\n\n(Auto-generated by runner)\n",
+            feature_key, feature_key, status_str
+        );
+        std::fs::write(path, content)
+            .with_context(|| format!("無法建立狀態檔案：{}", path.display()))?;
+    }
+
+    Ok(())
+}
+
 // ============================================================================
 // 功能資訊
 // ============================================================================
@@ -398,4 +454,65 @@ LAST_DONE="p2"
             FeatureStatus::P1DoneIntDeployed
         );
     }
+
+    #[test]
+    fn test_expected_status_for_step() {
+        assert_eq!(expected_status_for_step(Step::None), FeatureStatus::Unknown);
+        assert_eq!(
+            expected_status_for_step(Step::P1),
+            FeatureStatus::P1DoneIntDeployed
+        );
+        assert_eq!(
+            expected_status_for_step(Step::P2),
+            FeatureStatus::P2E2EPassed
+        );
+        assert_eq!(
+            expected_status_for_step(Step::P3),
+            FeatureStatus::P3RefactoredIntDeployed
+        );
+        assert_eq!(expected_status_for_step(Step::P4), FeatureStatus::Ready);
+    }
+
+    #[test]
+    fn test_update_state_status_creates_file() {
+        let temp_dir = std::env::temp_dir().join("test_state_md");
+        std::fs::create_dir_all(&temp_dir).unwrap();
+        let state_file = temp_dir.join("STATE.md");
+
+        // 確保檔案不存在
+        let _ = std::fs::remove_file(&state_file);
+
+        // 建立新檔案
+        update_state_status(&state_file, "test-feature", FeatureStatus::Ready).unwrap();
+
+        let content = std::fs::read_to_string(&state_file).unwrap();
+        assert!(content.contains("STATUS: READY"));
+        assert!(content.contains("FEATURE_KEY: test-feature"));
+
+        // 清理
+        let _ = std::fs::remove_file(&state_file);
+        let _ = std::fs::remove_dir(&temp_dir);
+    }
+
+    #[test]
+    fn test_update_state_status_updates_existing() {
+        let temp_dir = std::env::temp_dir().join("test_state_md_update");
+        std::fs::create_dir_all(&temp_dir).unwrap();
+        let state_file = temp_dir.join("STATE.md");
+
+        // 建立初始檔案
+        std::fs::write(&state_file, "# Test\n\nSTATUS: P1_DONE_DEPLOYED\n\nSome content").unwrap();
+
+        // 更新狀態
+        update_state_status(&state_file, "test-feature", FeatureStatus::Ready).unwrap();
+
+        let content = std::fs::read_to_string(&state_file).unwrap();
+        assert!(content.contains("STATUS: READY"));
+        assert!(!content.contains("P1_DONE_DEPLOYED"));
+        assert!(content.contains("Some content"));
+
+        // 清理
+        let _ = std::fs::remove_file(&state_file);
+        let _ = std::fs::remove_dir(&temp_dir);
+    }
 }